Enrollment Survey

The Enrollment Survey is completed by all twin pairs to enroll in the Washington State Twin Registry. Twins are asked to provide their cotwin’s contact information on the survey. This allows us to invite their cotwin to participate as well. The survey provides researchers with basic health information which they can use to publish papers, apply for grants, and recruit for studies.

The survey has evolved over the years. New questions that may be of interest to researchers have been added. Questions which do not provide researchers with the best information have been changed or removed. For example, the first Enrollment Survey, which was sent out from 2002-2007, included a question about race that only allowed respondents to choose one answer and included Hispanic/Latino as a race option. This question was updated in 2007 to reflect current NIH & US Census guidelines for reporting race and ethnicity. It now allows respondents to choose more than one answer and to report ethnicity (Hispanic/Latino) separately.

Associations between changes in resilient coping and posttraumatic stress disorder symptoms

Sinclair VG, Adams SM, Dietrich M. The pervasive, damaging nature of posttraumatic stress disorder (PTSD) presents enormous clinical challenges. Understanding the relationship between patients’ perceptions of PTSD symptoms and resilient coping strategies may prompt investigation of clinical interventions that improve adaptive, resilient coping skills. In this study, we examined whether changes in resilient coping were […]

Sleep Duration and Post-Traumatic Stress Disorder Symptoms: A Twin Study

McCall CA, Turkheimer E, Tsang S, Avery A, Duncan GE, Watson NF. Study Objectives Long and short sleep duration are associated with greater risk of developing post-traumatic stress disorder (PTSD); however, it is unknown how genetic and environmental influences impact this relationship. Thus, we investigated the association between sleep duration and PTSD symptoms using twin […]

Differential models of twin correlations in skew for body-mass index (BMI)

Tsang S, Duncan GE, Dinescu D, Turkheimer E. Background Body Mass Index (BMI), like most human phenotypes, is substantially heritable. However, BMI is not normally distributed; the skew appears to be structural, and increases as a function of age. Moreover, twin correlations for BMI commonly violate the assumptions of the most common variety of the […]

Examination of Cross-Sectional Associations of Neighborhood Deprivation and Alcohol Outlet Density With Hazardous Drinking Using a Twin Design

Rhew IC, Kosterman R, Duncan GE, Mair C. Objective The purpose of this study was to examine whether neighborhood socioeconomic deprivation and alcohol outlet density are associated with hazardous drinking using a co-twin design to control for confounding because of genetic and shared environmental factors. Method The study sample included cross-sectional data from 1,996 same-sex […]

Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts

Silventoinen K, Jelenkovic A, Hopper JL, Busjahn A, Cozen W, Mack TM, Sumathipala A, Harris JR, Goldberg JH, Harden KP, Duncan GE, Buchwald D, Turkheimer E, Kaprio J, et al. Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences […]

Cross-sectional association between soda consumption and body mass index in a community-based sample of twins

Eney AE, Tsang S, Delaney JA, Turkheimer E, Duncan GE. Background Consumption of sugar-sweetened beverages, such as soda, have been shown to play an important role in weight gain. Although soda consumption has been associated with body mass index (BMI) in many studies, it has been difficult to ascertain a true causal relationship between soda […]

Differences in genetic and environmental variation in adult body mass index by sex, age, time period, and region: an individual-based pooled analysis of 40 twin cohorts

Silventoinen K, Jelenkovic A, Cozen W, Mack T, Sumathipala A, Christensen K, Busjahn A, Duncan GE, Buchwald D, Goldberg JH, Hopper JL, Sung J, Turkheimer E, Kaprio J, et al. Background  Genes and the environment contribute to variation in adult body mass index [BMI (in kg/m2)], but factors modifying these variance components are poorly understood. […]

Neighborhood walkability moderates the association between low back pain and physical activity: A co-twin control study

Zadro JR, Shirley D, Pinheiro MB, Bauman A, Duncan GE, Ferreira PH. The aim of this study was to investigate whether neighborhood walkability moderates the association between low back pain (LBP) and physical activity (PA), using a co-twin design to control for genetics and shared environmental factors. A cross-sectional analysis was performed on 10,228 twins […]

Does the sex of one’s co-twin affect height and BMI in adulthood? A study of dizygotic adult twins from 31 cohorts

Bogl LH, Jelenkovic A, Christensen K, Cozen W, Mack TM, Duncan GE, Buchwald D, Hopper JL, Silventoinen K, Kaprio J, et al. Background The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric […]

Neighborhood deprivation and depression in adult twins: genetics and gene×environment interaction

Strachan E, Duncan G, Horn E, Turkheimer E. Background Depression is a significant problem and it is vital to understand its underlying causes and related policy implications. Neighborhood characteristics are implicated in depression but the nature of this association is unclear. Unobserved or unmeasured factors may confound the relationship. This study addresses confounding in a […]

Genetic and environmental influences on adult human height across birth cohorts from 1886 to 1994

Jelenkovic A, Sumathipala A, Christensen K, Hopper JL, Cozen W, Mack TM, Sung J, Duncan GE, Buchwald D, Harris JR, Goldberg JH, Kaprio J, Silventoinen K, et al. Human height variation is determined by genetic and environmental factors, but it remains unclear whether their influences differ across birth-year cohorts. We conducted an individual-based pooled analysis […]

Genetic and environmental effects on body mass index from infancy to the onset of adulthood: an individual-based pooled analysis of 45 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) study

Silventoinen K, Jelenkovic A, Busjahn A, Cozen W, Mack TM, Craig JM, Harden KP, Duncan GE, Buchwald D, Goldberg JH, Kaprio J, et al. Background Both genetic and environmental factors are known to affect body mass index (BMI), but detailed understanding of how their effects differ during childhood and adolescence is lacking. Objectives We analyzed […]

Genetic and environmental influences on height from infancy to early adulthood: An individual-based pooled analysis of 45 twin cohorts

Jelenkovic A, Craig JM, Sumathipala A, Harden KP, Cozen W, Mack TM, Hopper JL, Duncan GE, Buchwald D, Sung J, Harris JR, Busjahn A, Goldberg JH, Kaprio J, Silventoinen K, et al. Height variation is known to be determined by both genetic and environmental factors, but a systematic description of how their influences differ by sex, age and […]

Socioeconomic modifiers of genetic and environmental influences on body mass index in adult twins

Dinescu D, Horn EE, Duncan G, Turkheimer E Objective Individual measures of socioeconomic status (SES) suppress genetic variance in body mass index (BMI). Our objective was to examine the influence of both individual-level (i.e., educational attainment, household income) and macrolevel (i.e., neighborhood socioeconomic advantage) SES indicators on genetic contributions to BMI. Method The study used […]

Sleep Duration and Area-Level Deprivation in Twins

Watson NF, Horn E, Duncan GE, Buchwald D, Vitiello MV, Turkheimer E Study Objectives We used quantitative genetic models to assess whether area-level deprivation as indicated by the Singh Index predicts shorter sleep duration and modifies its underlying genetic and environmental contributions. Methods Participants were 4,218 adult twin pairs (2,377 monozygotic and 1,841 dizygotic) from […]

Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age: A Study of the CODATwins Project

Jelenkovic A, Craig JM, Sumathipala A, Harden KP, Cozen W, Mack TM, Hopper JL, Duncan GE, Buchwald D, Sung J, Harris JR, Busjahn A, Goldberg JH, Kaprio J, Silventoinen K, et al. A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference […]

The CODATwins Project

The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits Silventoinen K, Craig JM, Sumathipala A, Harden KP, Cozen W, Mack TM, Hopper JL, Duncan GE, Buchwald D, Sung J, Harris JR, Busjahn A, Goldberg JH, Kaprio J, et al. […]

Associations Between Fast-Food Consumption and Body Mass Index: A Cross-Sectional Study in Adult Twins

Cohen-Cline H, Lau R, Moudon AV, Turkheimer E, Duncan GE Obesity is a substantial health problem in the United States, and is associated with many chronic diseases. Previous studies have linked poor dietary habits to obesity. This cross-sectional study aimed to identify the association between body mass index (BMI) and fast-food consumption among 669 same-sex […]

Behavioral and Environmental Modification of the Genetic Influence on Body Mass Index: A Twin Study

Horn EE, Turkheimer E, Strachan E, Duncan GE Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such […]

Access to green space, physical activity and mental health: a twin study

Cohen-Cline H, Turkheimer E, Duncan GE Increasing global urbanisation has resulted in a greater proportion of the world’s population becoming exposed to risk factors unique to urban areas, and understanding these effects on public health is essential. The aim of this study was to examine the association between access to green space and mental health […]